Rupture of the transverse uterine scar after lower segment caesarean section.

THE lengthening list of indications for Caesarean section makes the management of subsequent deliveries a problem which confronts the obstetrician with ever-increasing frequency. Where the original Caesarean section was performed for a non-recurrent indication, subsequent vaginal delivery may reasonably be expected, and it is customary to allow such patients to go into labour. Even where elective repeat Caesarean section has been decided on, some obstetricians defer operation till labour has started and the lower segment is well formed. The number of occasions, therefore, on which the area of the previous scar is subjected to the strain of labour must be considerable. Experience has shown that the claims made by the protagonists of the lower segment operation that the scar of the transverse uterine incision is less liable than the scar of the classical incision to rupture under the strain of subsequent pregnancy and labour are justified. The occurrence of z cases of rupture of the lower segment scar in the practice of the Maternity Hospital at Leeds serves as a reminder that this danger, however remote, is one which deserves due consideration when deciding the method of subsequent delivery. The magnitude of this danger is difficult to assess. Holland’s figures for the classical operation have no exact counterpart for the lower segment operation, though numerous analyses of large series of lower segment operations have been published in which a numerical estimate of this risk is made: the figures given suggest that the risk of rupture of the lower segment scar is about one-tenth that of the classical scar, but since the data from which these calculations are made are not always clearly stated, it is difficult to accept them as authoritative. An effort has therefore been made to supply this deficiency by examining the records of women delivered in this hospital after a previous. lower segment operation, irrespective of: whether the original operation was per-. farmed in the hospital or elsewhere, Among this series of cases in which the uterine scar was tested by subsequent preg nancy and labour, rupture of the scar occurred twice. Analysis of Pregnancies following lower segment Caesarean section (transverse uterine incision) 1931-1948 :